Cavities can lower risk of head and neck cancers? Expert not convinced

September 16, 2013
| by Denise Heady

Cavities – commonly regarded as a sign of poor oral health – might not be so bad after all, suggests a new study linking cavities to a decrease in the risk of some cancers. But don’t toss the toothbrush just yet.

An expert affiliated with City of Hope found the study to be extremely limited, so limited in fact that he doubts the findings.

"The authors and correlation do not prove cause and effect," said Joel Epstein, D.M.D., M.S.D., a consultant with the Division of Otolaryngology/Head and Neck Surgery at City of Hope. "Also, even if caries [or cavities] are associated with reduced cancer risk –seems very unlikely – the dental damage, and infection risk of dental disease carries its own risk."

The study, published inJAMA Otolaryngology - Head & Neck Surgery and led by researchers at the University at Buffalo, State University of New York, found that people with the most cavities in their teeth are significantly less likely to be diagnosed for some head and neck cancers, compared to those with the fewest cavities.

The researchers suggested that lactic acid bacteria, which are produced by cavities, may be protective against cancer cells.

"These bacteria have important roles in digestion, as well as in local mucosal and systemic immunity, and their reduction has been associated with chronic inflammatory diseases, allergies, obesity and cancer," said lead researcher Mine Tezal, D.D.S., Ph.D., in an interview with HealthDay.

Almost 53,000 Americans will be diagnosed with head and neck cancers in 2013, and nearly 12,000 people will die from them, according to the American Cancer Society.

In their analysis, the researchers assessed data on 399 patients who had been diagnosed with head and neck cancers between 1999 and 2007, and compared it to data on 221 similar people who hadn’t been diagnosed with cancer.

After evaluating the two groups, researchers found that the people with the most cavities were the least likely to have head and neck cancers. This group had a 32 percent lower risk even after taking into consideration other factors such as gender, marital status, smoking and alcohol use.

Epstein cautioned, however, that the study had many limitations, including a small size and a focus on current cavities only, rather than a lifetime history of cavities.

Further, he said, tooth loss early in life is typically related to cavities and trauma, and tooth loss late in life is typically related to periodontal disease. These were not assessed. Further, he pointed out, cavities were used in effect as surrogates for lactobacilli, not as direct proof of lactobacilli.

“The in vitro or animal studies that must be done are not done; this is a real problem of statistical correlation," Epstein said.

Tezal agreed that the findings don’t mean people should let cavities develop in hopes of preventing [head and neck] cancers.

“The main message is to avoid things that would shift the balance in normal microbial ecology, including overuse of antimicrobial products and smoking. Rather, you should maintain a healthy diet and good oral hygiene, by brushing and flossing," she told HealthDay.